mp#

Materials.mp(lab='', mat='', c0='', c1='', c2='', c3='', c4='', **kwargs)#

Defines a linear material property as a constant or a function of temperature.

Mechanical APDL Command: MP

Parameters:
labstr

Valid material property label. Applicable labels are listed under “Material Properties” in the input table for each element type in the Element Reference.

  • ALPD - Mass matrix multiplier for damping.

  • ALPX - Secant coefficients of thermal expansion (also ALPY, ALPZ).

  • BETD - Stiffness matrix multiplier for damping.

  • BETX - Coefficient of diffusion expansion (also BETY, BETZ)

  • BVIS - Bulk viscosity

  • C - Specific heat

  • CREF - Reference concentration (may not be temperature dependent)

  • CSAT - Saturated concentration

  • CTEX - Instantaneous coefficients of thermal expansion (also CTEY, CTEZ)

  • CVH - Heat coefficient at constant volume per unit of mass

  • DENS - Mass density.

  • DMPR - Damping ratio.

  • DMPS - Constant structural damping coefficient.

  • DXX - Diffusivity coefficients (also DYY, DZZ)

  • EMIS - Emissivity. For default behavior, see Notes.

  • ENTH - Enthalpy. See Considerations for Enthalpy.

  • EX - Elastic moduli (also EY, EZ)

  • GXY - Shear moduli (also GYZ, GXZ)

  • HF - Convection or film coefficient

  • KXX - Thermal conductivities (also KYY, KZZ)

  • LSST - Electric loss tangent

  • LSSM - Magnetic loss tangent

  • MGXX - Magnetic coercive forces (also MGYY, MGZZ)

  • MURX - Magnetic relative permeabilities (also MURY, MURZ)

  • MU - Coefficient of friction

  • NUXY - Minor Poisson’s ratios (also NUYZ, NUXZ) (NUXY = ν:sub:yx, as described in Stress-Strain Relationships

  • PERX - Electric relative permittivities (also PERY, PERZ)

    If you enter permittivity values less than 1 for SOLID5, PLANE13, or SOLID98, the program interprets the values as absolute permittivity. Values input for PLANE222, PLANE223, SOLID225, SOLID226, or SOLID227 are always interpreted as relative permittivity.

  • PRXY - Major Poisson’s ratios (also PRYZ, PRXZ) (PRXY = ν:sub:xy, as described in Stress-Strain Relationships

  • QRATE - Heat generation rate for thermal mass element MASS71. Fraction of plastic work converted to heat (Taylor-Quinney coefficient) or fraction of viscoelastic loss converted to heat for coupled- field elements PLANE222, PLANE223, SOLID225, SOLID226, and SOLID227.

  • REFT - Reference temperature. Must be defined as a constant; C1 through C4 are ignored.

  • RH - Hall Coefficient.

  • RSVX - Electrical resistivities (also RSVY, RSVZ).

  • SBKX - Seebeck coefficients (also SBKY, SBKZ).

  • SONC - Sonic velocity.

  • THSX - Thermal strain (also THSY, THSZ).

  • VISC - Viscosity.

matstr

Material reference number to be associated with the elements (defaults to the current MAT setting ( mat )).

c0str

Material property value, or if a property-versus-temperature polynomial is being defined, the constant term in the polynomial. C0 can also be a table name (tabname); if C0 is a table name, C1 through C4 are ignored.

c1str

Coefficients of the linear, quadratic, cubic, and quartic terms, respectively, in the property- versus-temperature polynomial. Leave blank (or set to zero) for a constant material property.

c2str

Coefficients of the linear, quadratic, cubic, and quartic terms, respectively, in the property- versus-temperature polynomial. Leave blank (or set to zero) for a constant material property.

c3str

Coefficients of the linear, quadratic, cubic, and quartic terms, respectively, in the property- versus-temperature polynomial. Leave blank (or set to zero) for a constant material property.

c4str

Coefficients of the linear, quadratic, cubic, and quartic terms, respectively, in the property- versus-temperature polynomial. Leave blank (or set to zero) for a constant material property.

Notes

mp defines a linear material property as a constant or in terms of a fourth order polynomial as a function of temperature. (See the tb command for nonlinear material property input.) Linear material properties typically require a single substep for solution, whereas nonlinear material properties require multiple substeps.

If the constants C1 - C4 are input, the polynomial

Property = C0 + C1 (T) + C2 (T) 2 + C3 (T) 3 + C4 (T) 4

is evaluated at discrete temperature points with linear interpolation between points (that is, a piecewise linear representation) and a constant-valued extrapolation beyond the extreme points. First-order properties use two discrete points (±9999°). The mptemp or mptgen commands must be used for second and higher order properties to define appropriate temperature steps. To ensure that the number of temperatures defined via the mptemp and mptgen commands is minimally sufficient for a reasonable representation of the curve, Mechanical APDL generates an error message if the number is less than N, and a warning message if the number is less than 2N. The value N represents the highest coefficient used; for example, if C3 is nonzero and C4 is zero, a cubic curve is being used which is defined using 4 coefficients so that N = 4.

Some elements (for example, FLUID116 ) support tabular input for material properties. Use the dim command to create the table of property values as a function of the independent variables. Then input this table name ( C0 = tabname) when defining the property via the mp command. Tabular material properties are calculated before the first iteration (that is, using initial values ( ic )). For a list of elements that support tabular material properties and associated primary variables, see Defining Linear Material Properties Using Tabular Input

When defining a reference temperature ( mp,REFT), you can convert temperature-dependent secant coefficients of thermal expansion (SCTE) data from the definition temperature to the reference temperature. To do so, issue the mpamod command.

This command is also valid in SOLUTION.

Considerations for Enthalpy ( Lab = ENTH)#

  • To ensure correct results, you must define enthalpy over a large enough temperature range to span all computed temperatures during the solution. The tb command does not extrapolate enthalpy values beyond the specified temp range like the mp command does.

  • If both the tb and mp commands are used to specify enthalpy values, enthalpy values defined via the tb command are used and those defined via the mp command are ignored.

Default behavior for Emissivity ( Lab = EMIS)#

There is no command default value for emissivity, and you must specify it by issuing mp,EMIS. Otherwise, an error message appears. If you issue mp,EMIS without specifying C0, C1, C2, C3, C4 values, emissivity defaults to 0.

This command contains some tables and extra information which can be inspected in the original documentation pointed above.